MONTICELLO — Xcel Energy should work to improve the “degraded” performance of its Monticello nuclear plant, a top Nuclear Regulatory Commission official said.

Regional administrator Cynthia Pederson said that Xcel needs to understand the “depth and breadth” of performance issues and correct them.

Pederson visited Monticello for an annual regulatory meeting for plant workers and the community. Pederson said Monticello is a safe nuclear reactor, but managers need to clean up several examples of improper procedure.

NRC inspectors last June said Monticello wasn’t prepared for worst-case flooding along the Mississippi River. The finding was classified as having “substantial safety significance,” one step below the most serious rating in NRC’s system.

Xcel said it has fixed that problem by putting dike-building materials in case of a  flood.

Pederson said the NRC remains concerned with several lesser findings at the plant that showed weakness in human performance. She said NRC plans extra inspections this year to make sure Xcel is taking care of their concerns.

Karen Fili, Xcel’s site vice president at Monticello, said the utility has plans to improve performance.

The scrutiny comes as Minnesota utility regulators are examining whether it was a good decision for Xcel to spend $665 million to extend the Monticello plant’s life.

The upgrade cost more than double the original estimate.